US Army Corps of EngineersBUILDING STRONG®

Impact of Beetle Infestation on HydrologyDr. Christopher A. HiemstraCold Regions Res. and Engr. Lab. (CRREL)U.S. Army Corps of EngineersFort Wainwright, AK

Christopher.A.Hiemstra@usace.army.miloffice: (907) 361-5488 mobile: (907) 347-1028

November 2010

BUILDING STRONG®

Favorable Conditions for Beetles

Even-aged forests Drought-stressed trees Warmer winters (higher beetle survival)

Lodgepole pine trees are experiencing high mortality, as seen by their red coloration. In this August 2007 aerial image of the Fraser Experimental Forest, Colorado, dead reddened trees cover vast areas.

BUILDING STRONG®

Widespread Impact

Raffa et al. 2008

BUILDING STRONG®

Kelly Elder

BUILDING STRONG®Soil

Snow

Interception

Litter

TranspirationSnow MeltInfiltrationRunoff

InterceptionInterception

PrecipitationThroughfallWind SpeedSublimation

BUILDING STRONG®

Potential Impacts Pre-disturbance

► Canopy intercepts ~20-36% of snow► transpiration is ~38% of precipitation► higher shading, slower spring melt

Post-disturbance► lower interception► higher sublimation, evaporation, and radiation► faster runoff, earlier hydrograph peak

Unknowns► Transpiration (forest floor compensation?)► Runoff (greater or lower; spatially variable?)

BUILDING STRONG®

Watershed Research (Uunila et al. 2006)

BUILDING STRONG®

Snow Modeling (Bewley et al. 2010)

Baker Creek, BC, Canada (1570 km2) Lodgepole pine with 50-80% mortality 10-20% increase in peak SWE 10-15% faster melt rate